Effective placement of gravel packs is difficult, especially in deviated wellbores. Since viscous gels are usually used to transport the gravel during placement, the gravel has been observed (in model studies) to aggregate and concentrate in some areas while in other areas the gravel remains suspended until the gel breaks. Once the gel breaks, the reduction in viscosity allows the suspended gravel to settle leaving void spaces in the gravel pack (known as "holidays").
When producing hydrocarbonaceous fluids from a subterranean formation, formation fines accumulate in the void spaces. Accumulation of fines in said spaces causes a loss of efficiency resulting in reduced production capacity. Continued loss of production capacity eventually leads to the well being shut down and the gravel pack being replaced. Unscheduled gravel pack replacement increases operating costs. Therefore, what is needed is an effective means of repacking a gravel pack in situ to remove void spaces.